Home
Sieyuan supplied a 20 MW / 80 MWh grid-forming BESS with black-start capability to a remote load centre in southern Mongolia.
Sieyuan Grid-Forming BESS Strengthens Grid Stability in Mongolia
Sieyuan Electric supplied a 20 MW / 80 MWh grid-forming BESS for a remote area in southern Mongolia. Located at the end of a 180 km transmission line, the area had experienced frequent power interruptions. The system integrates black-start capability with PV-coordinated off-grid operation to support stable power supply during grid outages.
Project Overview
Sieyuan supplied a 20 MW / 80 MWh grid-forming BESS with black-start capability to a remote load centre in southern Mongolia.
Project Background
A Gobi load centre at the end of a 180 km line, with frequent supply interruptions.
Key Challenges
−40 °C to 40 °C swings, a fixed grid-connection window and 110 kV black-start duty.
Sieyuan Solution
Dual-circuit liquid cooling, modular production and self-developed VSG grid-forming control.
Technical Highlights
A 110 kV black start restoring a substation 15 km away in 60 seconds, witnessed by DNV.
Project Overview
Project Background
The project serves a remote load center in Mongolia's Gobi region, where long transmission distances and harsh climatic conditions affect power supply reliability. A renewable power plant was developed to improve local energy security. Sieyuan's grid-forming BESS provides voltage and frequency support, black-start capability, and coordinated operation with PV generation, enabling the system to maintain power supply under grid outage conditions.
Key Challenges
- Harsh gobi climate — The project faces temperatures ranging from -40°C in winter to 40°C in summer, placing high demands on battery and power conversion system thermal management and operational reliability.
- Tight delivery schedule — The project faced a tight delivery schedule, with the timeline closely aligned with a predefined grid-connection window and little room for delay. Meeting the schedule required efficient coordination across production and logistics.
- Black-start and off-grid operation — Following a complete loss of the main grid, the BESS needed to establish stable voltage and frequency at the 110 kV level and maintain islanded operation with PV generation for several hours.
Sieyuan Solution
- Integrated thermal management — Both battery and PCS containers use liquid cooling with dual-circuit cooling units and component-level thermal management. The system maintains an internal temperature of 25–30°C to support stable operation under demanding environmental conditions.
- Agile manufacturing and delivery — Sieyuan leveraged modular production and coordinated supply chain management to shorten the production cycle by approximately 20% compared with typical industry timelines, supporting the required delivery schedule.
- Grid-forming control — Sieyuan's self-developed VSG-based control technology enables the BESS to establish and maintain voltage and frequency, supporting black-start and off-grid operation. The system has also completed grid-forming performance tests conducted by the China Electric Power Research Institute (CEPRI).
Technical Highlights
- 110 kV black-start verification — The BESS successfully completed a field black-start test at the 110 kV voltage level, restoring power to a substation approximately 15 km away within 60 seconds.
- PV-BESS off-grid operation — Following grid loss, the system maintained stable islanded operation in coordination with PV generation for several hours. The test was witnessed by DNV, and an official witness report was subsequently issued.
- Compact and pre-assembled design — The AC/DC integrated design with a mirror back-to-back layout reduces land requirements by 30%. The system is fully assembled and shipped as an integrated unit, reducing on-site assembly work and accelerating deployment.
